Nonvolatile memory devices that utilize error correction estimates to increase reliability of error detection and correction operations

Abstract

Example embodiments may provide a memory device and memory data reading method. The memory device according to example embodiments may include a multi-bit cell array, an error detector which may read a first data page from a memory page in the multi-bit cell array and may detect an error-bit of the first data page, and an estimator which may identify a multi-bit cell where the error-bit is stored and may estimate data stored in the identified multi-bit cell among data of a second data page. Therefore, the memory device and memory data reading method may have an effect of reducing an error when reading data stored in the multi-bit cell and monitoring a state of the multi-bit cell without additional overhead.

1. A memory device comprising:
 an array of multi-bit nonvolatile memory cells; 
 an error detector configured to detect a first error in a first page of first-bit data read from a first plurality of multi-bit nonvolatile memory cells in said array during a first error detection operation and further configured to perform a second error detection operation on a second page of second-bit data read from the first plurality of multi-bit nonvolatile memory cells using an estimate of a second-bit datum in the second page of the second-bit data as a read data value having a higher priority of accuracy relative to other read data values within the second page of second-bit data; and 
 an estimator configured to identify a first multi-bit cell in the first plurality of multi-bit nonvolatile memory cells containing the first error and further configured to generate the estimate as a value of a second bit of data in the first multi-bit cell that is predicted by the first error. 
 
     
     
       2. The memory device of  claim 1 , wherein said estimator uses a mapping relationship between a threshold voltage of the first multi-bit cell containing the first error and a multi-bit data value associated with a different threshold voltage to generate the estimate. 
     
     
       3. The memory device of  claim 1 , wherein said error detector uses an error control code to detect the first error. 
     
     
       4. The memory device of  claim 1 , wherein said error detector is configured to use the estimate as a read data value having a higher priority of accuracy relative to all other read data values within the second page of second-bit data. 
     
     
       5. A nonvolatile memory device, comprising:
 an array of nonvolatile memory cells configured to store M-bits of data per cell, where M is an integer greater than one; 
 a data estimator configured to generate an estimate of a second bit of data stored in a nonvolatile memory cell from an error detected in a first bit of data stored in the same nonvolatile memory cell during a first error detection operation performed on a first page of first-bit data read from a first plurality of nonvolatile memory cells in said array; and 
 an error detector configured to perform a second error detection operation on a second page of second-bit data read from the first plurality of multi-bit nonvolatile memory cells using the estimate of the second bit of data as a data value having a higher confidence of accuracy relative to other data values within the second page of second-bit data. 
 
     
     
       6. The memory device of  claim 5 , wherein the second bit of data is an LSB data bit and the first bit of data is an MSB data bit or vice versa. 
     
     
       7. The memory device of  claim 5 , wherein the first page of first-bit data is read from the first plurality of nonvolatile memory cells using a first read voltage level having a first magnitude to identify which first plurality of nonvolatile memory cells have threshold voltages above the first read voltage level and which first plurality of nonvolatile memory cells have threshold voltages below the first read voltage level; wherein the first bit of data stored in the nonvolatile memory cells corresponds to a first threshold voltage having a magnitude less than the first read voltage level; and wherein the estimate of the second bit of data corresponds to a second threshold voltage having a magnitude greater than the first read voltage level. 
     
     
       8. The memory device of  claim 5 , wherein the first page of first-bit data is read from the first plurality of nonvolatile memory cells using a first read voltage level having a first magnitude to identify which first plurality of nonvolatile memory cells have threshold voltages above the first read voltage level and which first plurality of nonvolatile memory cells have threshold voltages below the first read voltage level; wherein the first bit of data stored in the nonvolatile memory cells corresponds to a first threshold voltage having a magnitude greater than the first read voltage level; and wherein the estimate of the second bit of data corresponds to a second threshold voltage having a magnitude less than the first read voltage level.